Temperature-dependent molecular conduction measured by the electrochemical deposition of a platinum electrode in a lateral configuration

Temperature-dependent current–voltage $(I–V)$ characteristics of a molecule, 1,4-benzenedimethanethiol, was measured for $30K<T<300K$ by a method of contact made by the electrochemical deposition of a platinum electrode in a lateral configuration. The $I–V$ characteristics are nonlinear and asymmetric in the entire temperature range and the current decreases with decreasing temperature down to $40K$⁠. Below $40K$⁠, the $I–V$ characteristics become temperature independent. The asymmetric $I–V$ characteristics can be understood as arising from a better contact on one side (made by the self-assembled monolayer) than on the other side (made by the electrochemically deposited $Pt$ electrode). The activation energy of thermally activated conduction for $T>100K$ is typically $0.11eV$⁠. For $T<40K$⁠, the observed temperature independent $I–V$ characteristics are fitted to the Fowler–Nordheim tunneling expression with barrier height of $1–2eV$ depending on the contact strength of samples.